1. Field of the Invention
Aspects of the present invention generally relate to a sheet conveyance apparatus and an image forming system and, in particular, to ones configured to convey imbricate sheets while shifting them.
2. Description of Related Art
Conventionally, in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile apparatus, or a multifunction peripheral including these, a sheet with an image formed thereon is discharged to and stacked on a sheet stacking apparatus. In recent years, as a result of the advent of an office network, it has become general practice for a single image forming apparatus such as a printer or a copying machine to be used by a plurality of users. In the case where a single image forming apparatus is shared by a plurality of users, a sheet bundle may be extracted without any doubt if only one sheet bundle is discharge onto the sheet stacking apparatus or when the number of users who extract the sheet bundle is one. However, the extraction may take time and effort if a plurality of sheet bundles is extracted or if a plurality of users extracts the sheet bundles.
To solve an issue like this, there has been provided a sheet conveyance apparatus which while performing, for example, the conveyance of a sheet, moves the sheet in a widthwise direction orthogonal to the conveyance direction before discharging the sheet onto the sheet stacking apparatus (see Japanese Patent Application Laid-Open No. 2007-001761). By thus discharging the sheet after moving it in the widthwise direction, the sheet is stacked on the sheet stacking apparatus in a state in which it has been shifted in the widthwise direction. Accordingly, it is possible to stack sheets on the sheet stacking apparatus with the sheets shifted for from sheet bundle to sheet bundle and from user to user, so that sheets can be clearly distinguished from one another.
However, in such a conventional sheet conveyance apparatus, when sheets are discharged onto the sheet stacking apparatus while being shifted in succession, it is necessary for a shift unit to move in the widthwise direction from its home position to discharge a sheet and then to return to the home position before the next sheet enters. In the case where the operation of shifting a sheet is thus conducted for each sheet to be conveyed, there is a limitation in terms of productivity.
In order to improve the productivity, in recent years, there has become available an apparatus which is configured to convey sheets with images formed thereon in an imbricate state in which the sheets partially overlap each other in succession. However, when imbricate sheets are shifted, it is impossible to secure the requisite time for the shift unit to return the home position, which means it is impossible to shift the sheets.
The present invention is directed to a sheet conveyance apparatus and an image forming system capable of reliably shifting sheets partially overlapping with each other in the widthwise direction and discharging.